Adjustable magnetic shunt for laminated core structures



a: m Feb. l, 1949. w. sLlWlAK QE@ ADJUSTABLE MAGNETIC SHUNT FOR LAMINATED CORE STRUCTURES Filed Sept. 10, 1945 2 Sheets-Sheet l ifi: if i/ "21 2 Sheets-Sheet 2 INVENTOR.

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leb. 1949. W SLIWIAK ADJUSTABLE MAGNETIC SHUNT FOR LAMINATED CORE STRUCTURES Filed sept. 10, 1945 Patented Feb. l, 1949 ADJUSTABLE MAGNETIC SHUNT FOR LAMINATED CORE STRUCTURES Walter Sliwiak, Chicago, lll., assignor to Jederson Electric Company, Bellwood, lll., a corporation of Illinois Application September 10, 1945, Serial No. 615,275

8 Claims. (Cl. 171-119) This invention relates to a core structure for electromagnetic apparatus, and in particular to a lmagnetic shunting element, the dimensions of which can be regulated.

More speciilcally, it is the practice in certain types of electromagnetic apparatus to provide a magnetic shunt path around one or more of the coils. This magnetic shunt path comprises a shunting element of magnetic materia-1 which is of dimensions somewhat smaller lthan the gap or space into which it is iitted. 'I'hus an air gap is provided. 'I'he air gap is generally filled -by a piece of vulcanized ber or other nonmagnetic material. Inasmuch as this shunt path comprises the combination of a magnetic shunting element plus a piece of fiber which fit in the space between two legs of the core, the dimensions have to -be made to reasonably close tolerances, not only to maintain the parts in tight mechanical relationship, but also to provide the desired reluctance. Furthermore, after the parts are assembled, there is no way of changing the width of the air gap, and thereby the reluctance of the shunt path.

It is an object of this invention to provide a magnetic core structure including-a shunt path in which the reluctance of Ithe shunt path may beregulated.

It is a further object of this invention to provide a shunting element, the dimensions of which may be varied after it has been assembled into operative relationship with the remaining parts of the magnetic core structure, thereby providing a means for adjusting the reluctance of the shunt path.

It is a still further object to provide an adjustable shunting element of the type described which is capable of use in combination with core structures of various dimensions, and which is also capable of usein connection with gapping means of variable dimensions. Thus, a comparatively small number of shunting elements can be stocked, even though they are to be used in a great number of different types of core structures.

Further objects of this invention are .to provide a magnetic core structure made up of a plurality of elements, in which the members may be assembled in tight relationship without the necessity of driving the laminated elements into operative relationship, and also to provide a core structure including gapping material which embodies a certain amount of resilience so that the air gap can be regulated to a limited extent with- 2 out the necessity of substituting a gapping element of diii'erent dimensions.

Other objects, advantages and features will become apparent as the description proceeds.

With reference now to the drawings in which like reference numberals designate like parts,

Fig. 1 is a sectional view through a transformer embodying my invention;

Fig. 2 is a view similar to Fig. 1, but showing a modiiled form of my invention;

Fig. 3 is an enlarged sectional view of the shunting element shown in Fig. 2;

Fig. 4 is -a side view of the transformer shown in Fig. 1, showing the general arrangement of the parts;

Fig. 5 is a section similar to Fig. 3, showing a still further modiiication of my invention;

Fig. 6 is a detail of the washer shown in Fig. 5;

Fig. 7 is a view similar to Fig. 1, but showing a somewhat diierent embodiment of my invention;

Fig. 8 is an enlarged det-ail view 0f a portion of the shunting element; and

Fig. 9 is a detail view of .the channel element used in connection with .the shunting element.

With reference now to Figs. 1 and 4, which show my invention as applied to a simple shell type transformer, 4the reference numeral I 0 designates the core. The core includes legs Il, I2 and I3, and coils Il and I5 are disposed on the center leg I2. Coil I4 is separated from coil I5 by shunting elements I6 and I1. As shown in Fig. 1, each shunting element is made up of a `plurality of laminations I8 which are skewed with respect to the laminations which form the core proper. Each of the laminations is provided with two lapertures which are aligned with the corresponding apertures in the adjacent laminations in order to permit bolts I9 to be passed through the shunts. Nuts 20 are provided for the bolts, which permit the laminations to be drawn together. Gapping elements 2| of vulcanized ber, Bakelite, or other nonmagnetic material, are interposed between the shunts and `the core I0.

In operation it will be seen that as the nuts 20 29 may be provided as pointed out in connection with Fig. 1.V A still lfurther modification is shown in Fig. 5, the washers in this instance being spherical washers 30. In this arrangement the bore 28' may be of somewhat smaller dimensions, and the spherical washers 30 may be provided with slots 3|, as shown in Fig. 6. Thus the position of the bolt 24 and nut 25' may shift with respect to the spherical washers 30', as the parts are drawn up, the position of the bolt with respect to the bore 28' remaining substantially the same.

A further embodiment of the invention is shown in Figs. 'I and 9, inclusive.

In this embodiment, the shunting element 35 comprises two stacks of laminations 36 and 31, respectively, the laminations being designated by the reference numerals 39 and 39. The gapping element 4|) is disposed between the two stacks 36 and 31, and means are provided to` draw up both of the stacks so as to tend to align the laminations 33 and 39 with the laminations 4| of the core 42. Inother words, the action is somewhat similar to a toggle action. Bolts 43 and 44, together with cooperating nuts 45 and 46 bear on brackets 41 and 43, which engagethe ends of stacks 35 and 31.

The construction of bracket 41 is shown in Fig. 8, and comprises two plates 49 and 50 of relatively ilexible nonmagnetic material. The outer plate 49, may preferably be of brass or bronze, and the inner plate 50 may be of fiber. The bracket 43 is shown in Fig. 9 as an ordinary channel of nonmagnetic material, which is disposed across the concave side of the V, at the bottom of the shunting element 35.

Flexible plates 49 and 50 can conform themselves to the angle of the laminations 39 and 39 so that when the bolts 43 and 44 are tightened up. the distance between plate 49 and bracket 48 is shortened, thereby imposing a torque on the laminations 38 and 39. Thus the width of the stacks 35 and 31 is increased to provide a tight assembly on the parts, and narrow the air gap.

The principal advantages of the Fig. 7 construction are that there is no sliding contact between the stacks 3B and 31 and the core 42. By using a gapping material, such as certain types of vulcanized fiber or certain types of laminated Bakelite, whichis somewhat resilient, a

much finer adjustment of the air gap can be obtained. Inasmuch u the edge of the shunting element is serrated, due to the angular disposition of the separate laminations, a certain amount of resilience in the gapping element will permit a narrowing of the air gap due to the tendency of the resilient, or somewhat soft material, to flow into the indentations formed by the serrated edge, as the pressure of the projecting corners of the separate lamination is forced more deeply into the gapping element.

I have used the term shunting eiement herein in its broader sense as being a means of closing the magnetic gap, irrespective of whether the shunting element is disposed in the main magnetic path of the core, or whetheritforms a shunt path between branches of the main magnetic path.

The term gap," as used in the claims is used in its structural sense, that is, as indicating a space between two oppositely disposed surfaces of the core structure. For instance, the term gap indicates that portion of the core window in which the adjustable shunt is disposed, as shown in Figs. l and 4.

It is obvious that this invention is applicable to other types of electromagnetic apparatus than that shown herein and'various modifications and changes in the construction shown can be made without departing from the spirit of my invention as defined -by the appended claims.

I claim: l

1. In electromagnetic apparatus, a core structure comprising a substantially rigid assembly of elements providing two oppositely disposed spaced surfaces to form a gap, a separate laminated structure positioned in said gap and comprising a plurality of substantially rigid laminations disposed in skewed relationship, and adjustable means for compressing said laminated structure in a direction perpendicular to the length and width dimensions of said gap to expand the length dimension of said laminated structure. v Y

2. In electromagnetic apparatus, a core structure comprising a substantially rigid assembly of elements providing two oppositely disposed spaced surfaces to form a gap, a laminated structure positioned in said gap and comprising a plurality of laminations disposed in skewed relationship, adjustable means for compressing said laminated structure in a direction perpendicular to the length and width dimensions of said gap to expand the length dimension of said laminated structure, and additional elements disposed in said gap so that the expansion of said laminated structure` will cause all of said elements to be compressed together in said gap in self supporting relationship.

3. In electromagnetic apparatus, a laminated core providing a rectangular window of xed dimensions, a shunting element of adjustable Width disposed transversely in said window across the shorter dimension thereof, and gapping elements disposed between the ends of said adjustable shunting element and the surfaces of said core which form the side walls of said window, said gapping elements being formed from a slightly resilient material, said shunting element comprising a stack of laminations arranged in skewed relationship, a bolt passing through said stack, and a nut for said bolt.

4. In electromagnetic apparatus, a laminated core providing a gap of xed dimensions, a stack of substantially rigid laminations positioned in said gap, and disposed in skewed relationship with respect to the laminations of said core, and means passing through said stack of laminations and engaging the top and bottom laminations of said stack so -as to exert a pressure on said stack in such direction that the laminations thereof will tend to rotate into alignment with the laminations of said core, thereby extending the length of said stack and exerting a pressure against the core whereby said stack will be maintained in self-supporting relationship with respect to said core.

5. In electromagnetic apparatus, a laminated core providing a gap of xed dimensions, two stacks of laminations positioned in said gap, the laminations of each stack being disposed in skewed relationship with respect to the laminations of said core, and being oppositely skewed with respect to each other so as to form a V, a gapping element inserted between the abutting edges of the two stacks, and means to exert pressure on both of said stacks in a direction perpendicular to the laminations of said core, whereby the laminations of each stack tend to straighten out to increase their total length.

6. In combination, a core structure for electromagnetic apparatus comprising a substantially rigid assembly of elements providing two oppositely disposed substantially parallel spaced surfaces to form agap, and a magnetic shunting element disposed in said gap comprising a stack of laminations of magnetic material having aligned side edges and being arranged in skewed relationship with respect to their end edges, and adjustable compression means passing through said stack in a direction parallel to the side edges thereof, and engaging the top and bottom of said stack so that when said compression means are tightened up, a force couple will be exerted on said stack which will tend to straighten out the laminations thereof so that said end edges will react against said oppositely disposed surfaces of said core structure.

7. In combination, a core structure for electromagnetic apparatus comprising a substantially rigid assembly of elements providing two oppositely disposed substantially parallel spaced surfaces to form a gap, and a magnetic shunting element disposed in said gap comprising a stack of laminations of magnetic material having aligned side edges and being arranged in skewed relationship with respect to their end edges, a headed bolt passing through said stack in a direction parallel to the side edges thereof, a nut for said bolt, and conical washers interposed between the top lamination of said stack and the head oi said bolt. andbetweenthe bottom lamination of said 'stack and said nut, said shunting element being so disposed that said end edges will react against said oppositely disposed surfaces oi said core structure.

8. In combination, a core structure for electromagnetic apparatus comprising a substantially rigid assembly of elements providing two oppositely disposed substantially parallel spaced surfaces to form a gap, and a magnetic shunting element disposed in said gap comprising a stack o! laminations of magnetic material having aligned side edges and being arranged in skewed relationship with respect to their end edges, a headed bolt passing through said stack in a direction parallel to the side edges thereof, a nut for said bolt, and spherical washers interposed between the top lamination of said stack and the head of said bolt, and between the bottom lamination of said stack and said nut, said shunting element being so disposed that said end edges will react against said oppositely disposed surfaces of said core structure.

WALTER SLIWIAK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 349,611 Stanley Sept. 21, 1886 2,141,554 Reichard Dec. 27, 1938 2,180,759 Kneisley Nov. 21, 1939 2,331,128 MacNeil Oct. 5, 1943 FOREIGN PATENTS Number Country lDate 2,786 Great Britain Feb. 10, 1916 93.551 Sweden Dec. 2, 1938 421,353 Great Britain Dec. 13, 1934 

